1. Field of the Invention
The field of the invention is that of communications and in particular telephone communications.
To be more precise, the invention concerns a new approach to telephone terminals and a corresponding method of communication between a calling terminal and a called terminal.
2. Description of the Prior Art
At present, to establish a call between two terminals, the telephone number of a called terminal is entered by means of a calling terminal. The call can be a telephone call (voice transmission) or a multimedia call (voice and/or image and/or data transmission). In the conventional way, the calling terminal uses a predetermined communication network (generally the switched telephone network) to establish real time point to point communication enabling true interactivity between the two parties.
This conventional technique is advantageous in terms of user friendliness in particular. On the other hand, under some conditions it proves very costly. The call is generally billed according to duration and distance. The time period used as the basis for billing is sometimes very short, in particular when communicating with other countries. In this situation, it is not uncommon for the cost of a call to be upwards of ten dollars.
There are less costly communication systems. There is the INTERNET network, for example, where billing is not based on duration or distance. In the conventional way a single base unit on the telephone network enables exchange of data between Europe and Japan for hours at a time.
On the other hand, this network is often rather slow and does not provide real time information exchange, as is provided by the switched telephone network. The INTERNET is therefore essentially used to transfer data when off-line communication or at the very least a very low speed can be tolerated.
In some situations it is not necessary to set up a relatively high cost real time symmetrical call.
This applies if the called terminal is a facsimile machine, for example. The inventors have also realized that, even though this goes against received wisdom in the art, this applies also to an answering service (telephone, telematics or multimedia). It could therefore be highly feasible to set up an off-line call rather than a real time symmetrical call of higher cost.
One objective of the invention is to alleviate these various drawbacks of the prior art and to exploit the observations referred to above.
To be more precise, one objective of the present invention is to provide a calling terminal, a called terminal and a corresponding method of telephone communication between a calling terminal and a called terminal for optimizing the cost reduction of calls.
Another objective of the invention is to provide a calling terminal of the above kind that is compatible with existing called terminals and, conversely, a called terminal that is compatible with existing calling terminals.